An optical emitting circuit includes an array of M optical sources distributed in N groups, where N is lower than M. A controller is configured to generate N periodic square wave control signals that are successively mutually phase shifted by pi/N and that all have the same period, and to cyclically activate/deactivate all the optical sources of the N groups using the control signals. The optical emitting circuit is configured so that each group is activated when a corresponding control signal is in its first state and deactivated when the corresponding control signal is in its second state. The number of optical sources in each group and the order of the groups in the sequence of activations/deactivations are chosen so as to generate an optical signal having an amplitude that sinusoidally varies in steps.